Logical thinking re: blasting the fuckers

I had recently read that you shouldn't use nit lotion prophylactically (i.e. just in case) because that's how resistance grows.

Just now I'm thinking:

Arse. What a bunch of big sweaty bollocks. You use the stuff and

either

a) the little fuckers are there, and die. Or get resistant, in which case you keep trying till they go away, which is what you'd eventually have to do anyway, and the quicker you do, the less chance they have to spread.

or

b) the little fuckers are not there, in which case they cannot enjoy increased resistance, because they're not even fucking there to react to the stuff.